The technical field generally relates to NOx management of engines having a NOx aftertreatment system. The utilization of an EGR cooler bypass allows for aftertreatment temperature increases, while maintaining NOx control, in operation regions where such increases are desirable. EGR cooler bypassing further provides for increased operating life of the EGR cooler due to a lower overall exposure time to EGR gases, and especially lower temperature EGR gases. However, EGR cooler bypass is limited by the maximum temperature the system allows for the intake manifold and by system limitations due to increased temperature at the intake manifold—for example the reduced charge density of gases in the intake manifold. In certain operating regions of many engines, exhaust temperatures may be too low for optimal operation of the NOx aftertreatment (e.g. an SCR catalyst), and the operating limitations may disallow EGR cooler bypass operation at some of these certain operating regions.
Memory intensive control schemes for managing these complexities are undesirable. Increasing the onboard computing capability for a system increases the cost of the engine package, and this cost increase is exacerbated by the properties which the computer package must have to withstand the harsh operating environments that engine-related computers experience. Therefore, further technological developments are desirable in this area.